The long term objectives of this proposed research were a) to utilize laboratory psychophysical techniques of vision tests with a view to developing more sensitive clinical measures of the natural history in the retinal vascular disease of diabetic retinopathy; b) where possible, to correlate the functional vision losses with observed retinal vascular changes; and c) to provide specific hypotheses and sensitive measurement techniques to be used for a follow-on randomized clinical trial involving the treatment and management of diabetic retinopathy. The original proposal called for the development of psychophysical vision tests during the first year, and to begin a pilot group of patients and normal controls. Instrumentation has been developed to measure the following functions: sensitivity of chromatic and luminance functions, spatial and temporal contrast sensitivity, low contrast acuity, glare recovery, Stiles-Crawford effect, hue discrimination and light adaptation properties of flicker resolution. Pilot studies on insulin dependent diabetics with background retinopathy showed significant slowing of the glare recovery function.